LLVM 2.8 の C API 差分をチェックしてはじめて気づいたけど、2.8...

LLVM 2.8 の C API 差分をチェックしてはじめて気づいたけど、2.8 からは Union Type がなくなったみたい。

The LLVM IR ‘Union’ feature was removed. While this is a desirable feature for LLVM IR to support, the existing implementation was half baked and barely useful. We’d really like anyone interested to resurrect the work and finish it for a future release.

• LLVM 2.8 Release Notes | Major Changes and Removed Features
• [LLVMdev] Union type, is it really used or necessary?

現在の実装は不完全で、また、不足分を実装しメンテする開発者がおらず優先順位も低い、ということが理由のようだ。

It’s just a matter of priorities, unfortunately… :(

http://lists.cs.uiuc.edu/pipermail/llvmdev/2010-September/034451.html

Lots of people agree it would be a useful feature, we are lacking a useful implementation :-)

http://lists.cs.uiuc.edu/pipermail/llvmdev/2010-September/034484.html